We have a 93 LT1 which we have had for a few months. With the freezing temps around the corner I decided to check the coolant. It was a clean green color, but when I looked at the cap I noticed a redish brown mud type of material covering the spring under the cap. My understanding is that this often happens when the coolant is changed from the orange dexcool to green antifreeze. Should I flush the system and start over? If so which type of coolant should I use?

 

I think that's pretty normal? I kinda remember seeing a little rust-colored gunky liquid on on the cap spring on both my Vette and our van; neither of them ever had anything but green coolant.

Ben

 

needs to be changed. vettes only use ORANGE dexcool coolant. when it turns green its getting gunky! look where the coolant check tank is. open it. are the inside walls covered in green gunk? or has the coolant settled and there is gunk at the bottom? if either then get it flushed!

 

C4s do not use dexcool. Green stuff from the factory.

 

Except in '96.. It's the orange stuff.. Think that's the year GM switched.

For the '93, it's green only, don't try and change to dexcool, you'll just have problems..

 

Up until a few years ago, a cooling system flush at a dealer usually included the use of "cooling system sealant pellets" which was a stop-leak type of material. GM sells a set of 6 pellets in tablet form that you would break up and add to the expansion tank. They are brown in color and that may be what you see. GM issued a bulletin awhile back that recommended discontinuing the use of these pellets in Corvettes.

If you don't have any idea how old the coollant is in the car, I would have the system flushed and new green (ethlyene glycol) coolant installed. No Dexcool or other multi-use coolants! You can do this yourself but the service manual procedure is somewhat involved and it requires removal of the knock sensors at the botom of the block to insure you get all of the old coolant out. In addition, you do not want to get any water on the Opti-Spark as it will kill it and cost hundreds to replace.

If the hoses are original, it might be time to get the upper and lower radiator hoses replaced. The heater hoses should be fine but inspectthem for wear and cracks. Hoses are expensive so get prices before you start ripping out hoses!!

The factory service manual recommends a refill of 50% coolant and distilled water which is good for -34 degrees F.

 

on my radiator it specifically says use orange 13 dexcool only.
1996 is the best year... worked most the bugs out.
your friend
Sean Blanton

 

see mine is supposed to bed orange and i noticed it was green and gunky at the bottom of the check tank. and i never knew when the previous owner changed it. so i am getting it flushed!
good luck
your friend
Sean Blanton

 

That is just totally .
Dexcool will never turn green and ethylene glycol will never turn orange. "coolant settled??? I rest my case.

BLK/BLK'93,
Since the car is new, to you, and it is apparent the cooling system could use a flush, *I* would do a super thorough flush, including pulling the block drains/knock sensors. Green and orange antifreeze don't mix well and can cause a disaster. From your description, it sounds as though that may have been done in your car. Hence the recommendation for the THOROUGH flush. It sounds like the green was the original. You could probably use either after the flush. Contrary to the above quote, MY car originally came with the green, and has worked well for 20 years. I used to flush and change coolant every 2 years and I still have my original radiator core. I have never seen the "redish brown mud" on my cap or anywhere else. It sounds like it is time to catch up on some deferred maintenance.

RACE ON!!!

 

thanks for calling me a liar!
I swear to god that my coolant was orange on top and then green on the bottom! it had gunk stuck to the side of the coolant fill tank!
If i had pics i would show you! in all seriousness it was green, with gunk! not because they changed coolant!
thanks for your thoughts though.
agian its my car i saw it i had it flushed mechanic said it was about 40k over due!
thanks alot
your friend
Sean
yes was just relating my expirence to his didnt know that you guys had green coolant, because 96s use orange!



you

 

the reddish brown crud may be the remnants of the sealer pellets the factory used to put in the cooling system. i don't think there is anything to worry about.

if you don't know when the system was last flushed, you might as well get it done soon.

don't go with the orange stuff if you can help it. after seeing this "green+orange=ooze" theory pop up on the Forum for years, you might as well avoid the potential of running into this problem yourself. however, i have yet to see someone run a controlled experiment to see if this theory can be scientifically proven. but better err on the safe side, right?

 

I'm not calling you a liar, I'm just saying you are wrong. To lie, you'd have to know better. Based on that logic, all "vettes" must be Crossfires, right???

RACE ON!!!

 

Only late late 95's and all 96's came with the dexcool. A for 96 being the best it;s not acutally 95 is in 96 they switched to OBDII and used the dexcool junk to try and make changes and they are both changes for the worse.

95 is the exact same car except it doesn't have the dreaded OBDII and dexcool junk in it. Bad thing is once your coolant system has had one or the other in it you can't switch but you could try the new yellow which will mix with either. Get teh dex out of your car now I had a 96 chevy truck and bought it new and 4 years later it turned to gel nearly.

 

My only advice is stay with that came in the car.